Host processor systems may store and retrieve data using a storage device containing a plurality of host interface units (I/O modules), disk drives, and disk interface units (disk adapters). The host systems access the storage device through a plurality of channels provided therewith. Host systems provide data and access control information through the channels to the storage device and the storage device provides data to the host systems also through the channels. The host systems do not address the disk drives of the storage device directly, but rather, access what appears to the host systems as a plurality of logical disk units. The logical disk units may or may not correspond to any one of the actual disk drives. Allowing multiple host systems to access the single storage device unit allows the host systems to share data stored therein.
In some cases, it is desirable to use a cloud service to store and retrieve data. Cloud services generally provide on-demand service, broad network access, resource pooling, and rapid elasticity or expansion, and thus may be beneficial for many storage applications. In some cases, it may be desirable to integrate use of cloud services with use of conventional storage devices. However, often operations on cloud services are very different from operations on conventional storage devices. Furthermore, in some cases, there are operations on storage devices that are not directly available for cloud services and vice versa.
Accordingly, it is desirable to be able to integrate cloud services with conventional storage devices in a way that takes advantage of the strengths of both types of systems while providing for efficient and reliable storage.